The described technology relates to light-emitting devices and luminaires with a substantial total internal reflection (TIR) extractor.
Light-emitting elements (LEEs) are ubiquitous in the modern world, being used in applications ranging from general illumination (e.g., light bulbs) to lighting electronic information displays (e.g., backlights and front-lights for LCDs) to medical devices and therapeutics. Solid state lighting (SSL) devices, which include light-emitting diodes (LEDs), are increasingly being adopted in a variety of fields, promising low power consumption, high luminous efficacy and longevity, particularly in comparison to incandescent and other conventional light sources.
A luminaire is a lighting unit that provides means to hold, position, protect, and/or connect light-emitting elements to an electrical power source, and in some cases to distribute the light emitted by the LEE. One example of a LEE increasingly being used in luminaires is a so-called “white LED.” Conventional white LEDs typically include an LED that emits blue or ultraviolet light and a phosphor or other luminescent material. The device generates white light via down-conversion of blue or UV light from the LED (referred to as “pump light”) by the phosphor. Such devices are also referred to as phosphor-based LEDs (PLEDs). Although subject to losses due to light-conversion, various aspects of PLEDs promise reduced complexity, better cost efficiency and durability of PLED-based luminaires in comparison to other types of luminaires.
While new types of phosphors are being actively investigated and developed, configuration of PLED-based light-emitting devices, however, provides further challenges due to the properties of available luminescent materials. Challenges include light-energy losses from photon conversion, phosphor self-heating from Stokes loss, dependence of photon conversion properties on operating temperature, degradation from changes of the chemical and physical composition of phosphors as an effect of overheating, exposure to humidity or other damage, dependence of the conversion properties on intensity of light, propagation of light in undesired directions due to the random emission of converted light that is emitted from the phosphor, undesired chemical properties of phosphors, and controlled deposition of phosphors in light-emitting devices, for example.